feat(tpu): Add UNKNOWN to TPU node state, This state will be used to …

…prevent a node from being marked as READY during diagnose after it has failed repair (googleapis#11433)

- [ ] Regenerate this pull request now.

PiperOrigin-RevId: 714068635

Source-Link: https://togithub.com/googleapis/googleapis/commit/c3556b45dc35a145e04b5692bc72e01a4f58a6b2

Source-Link: https://togithub.com/googleapis/googleapis-gen/commit/651e1ce4c2b70cb145048e1f3de2fb8ee1800601
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